1. Field of the Invention
This invention relates to firing mechanisms for munitions and, more particularly, to a threaded ferrule and gasket combination for mounting a fuze and heat shield in the firing mechanism for a hand grenade, and the like.
2. Prior Art
An entirely satisfactory munition presents a number of difficult technical problems. The munition, for example, must be relatively inexpensive, as well as being easy and safe to manufacture. The munition, moreover, should enjoy reliable operation in spite of rough handling and exposure to extreme environmental conditions. Hand grenade firing mechanisms are a typical munition component that is subject to these foregoing basic requirements.
Ordinarily a hand grenade firing mechanism is threaded into the casing that contains the main explosive charge. A spring-loaded striker is held in a "cocked" position by means of a safety lever which, in turn, is secured to the body of the grenade through an extractable pin. If the pin is pulled from the safety lever, only the manual force pressing the grenade and the safety lever together in the palm of the hand keeps the striker in the "cocked" position. As the grenade is thrown, this manual force is removed and the biasing spring on the striker forces the striker to flip the safety lever off the grenade and slam the striker down on a percussion cap. The cap detonates to ignite the grenade's fuze. The fuze, after a predetermined period of burning, initiates the explosion of the main charger.
This basic mechanical combination is subject to a number of further conflicting requirements. A heat shield is provided, for example, between the fuze and the main charge to prevent a premature explosion. Frequently, this heat shield encloses the entire fuze in order to provide waterproofing for the fuze. This approach, however, has the unfortunate side effect of insulating the fuze from the main charge and thereby promoting misfires. If the fuze is not waterproofed, then water may enter the casing and impair detonator action by acting as a shock absorber.
Clearly there is a need to lodge the fuze securely within the grenade to obtain maximum impact effect from the striker. It is difficult to reconcile this need with a countervailing requirement for a fuze that can be removed from the grenade casing with relative ease for shipment to ammunition distribution points, and the like. Thus, if the fuze is loosely mounted within the casing to permit easy withdrawal, then the elasticity that is inherent in a loose mounting of this nature will attenuate striker impact and produce misfires and "duds".
Fuze insertion during grenade assembly introduces another major problem. In some grenades, the striker is held in a "cocked" condition by a blocking fixture as the fuze is inserted. The safety lever is mounted in place and the safety pin is then inserted into the safety lever to permit the striker blocking fixture to be removed. Unquestionably, this is a dangerous operation because an accidental striker release and subsequent grenade explosion always is a possibility.
Accordingly, there is a need for an improved fuze assembly that overcomes these difficulties that have characterized the prior art and reconciles the need for a waterproof, removable fuze with a heat shield of adequate length, in an assembly that enables the firing mechanism to be assembled more safely.